Document FR-0 704 251 discloses a fixing ring provided with snap-fastening catches at the ends of which snap-fastening lugs designed to be received under the shoulder on the neck are formed. A band then covers the ring to prevent the lugs from being released from under the shoulder. With that type of fixing device, it is possible to remove the ring from the neck so long as the band is not mounted. The snap-fastening catches are flexible, which makes it possible for the lugs to pass over the thick portion to reach the snap-fastening position under the shoulder. Therefore, on mounting the ring on such a neck, the catches must bend outwards, which increases the working diameter of the ring as it passes over the thick portion of the neck. In addition, the ring is permanently fixed only once the band has been mounted: the fixing thus requires two parts.
Document U.S. Pat. No. 4,773,553 discloses another fixing device in which the fixing ring is made of a plastically-deformable material and is provided with catches having heads initially projecting outwards. It is thus possible to mount the ring on the neck without deforming the catches outwards. Final fixing is achieved by engaging a band by force over the ring so that the outwardlyprojecting catches are brought back inwards under the shoulder on the neck by the material being deformed plastically. In which case, two parts are also necessary to perform the fixing, and, in addition, some force must be exerted on the band to cause the heads to deform inwards.
Document U.S. Pat. No. 5,299,703 describes a pump-fixing system in which a ring is provided with catches terminated by heads formed inwardly-projected bulges. Prior to being mounted the bulging heads are bent outwards to enable the neck to pass between them. Once in position on the neck of the container, the heads are deformed inwards by means of a band. That system is analogous to the system of Document U.S. Pat. No. 4,773,553, except that the ring is made of metal, and that the heads are bent inwards rather than being caused to deform plastically. Since the ring is made of metal, that system can be likened to crimping because the metal is deformed so as to reduce the inside diameter of the ring. It is also necessary to use a tool to fix the ring to the neck of the container.